1. Field of the Invention
The invention relates to a hybrid vehicle. More particularly, the invention relates to a hybrid vehicle including an internal combustion engine; a motor which can output power to a driving shaft coupled with an axle; and electric power storage means for storing electric power obtained by converting at least part of power from the internal combustion engine to electric power, and for supplying the electric power to the motor.
2. Description of the Related Art
As a hybrid vehicle of the above-mentioned type, Japanese Patent Laid-Open Publication No. 5-328526 discloses a hybrid vehicle which starts running by a motor using electric power supplied from a battery immediately after a start key is turned to an ON position. In the hybrid vehicle, an engine for electric power generation is then started when a temperature of a catalyst of an exhaust purifying device is increased to a predetermined temperature by a heater. In the hybrid vehicle, the engine is started after the temperature of the catalyst of the exhaust purifying device becomes a temperature at which the catalyst functions properly, so as to appropriately purify exhaust gas during engine start.
Generally, a hybrid vehicle includes a motor which can output power for running, and a secondary battery which supplies electric power to the motor. Accordingly, it is not necessary to start the internal combustion engine immediately after a start key is turned to an ON position. Therefore, it is proposed to make preparations for the start of the internal combustion engine (herein after, referred to as the “engine start”) so as to efficiently operate the internal combustion engine, and so as to make the exhaust gas clean during engine start. From this point of view, the applicant proposes a hybrid vehicle in which heat of an internal combustion engine during operation is stored, and the internal combustion engine is warmed up during the engine start using the stored heat (refer Japanese Patent Laid-Open Publication No. 2002-12206). The applicant also proposes a hybrid vehicle in which ON/OFF states of a controller and an inverter, whether to activate a motor, an ON/OFF state of an oil pump, and the like are set based on a position of a start key (refer to Japanese Patent Laid-Open Publication No. 9-286245).